Looks to be legit, it's a system email notification, but I'm not for sure why it sent you that. - Does it send you that everytime you send an email? - How did you send the email through Pingly that caused that email? (web app, iOS app, inbound SMTP) Thanks for the info!

I hadn't sent mail in 24 hrs, I use pingly on web.

Do you have any outside tools or servers sending email into pingly that uses your pingly email as the from address?

Yes